CVE-2022-22824Network attack vector

Denial of service via default-attribute allocation overflow

Published Jan 8, 2022 · Updated May 5, 2025

Integer overflow in Expat before 2.4.3 allows remote attackers to interrupt XML-parsing services via crafted XML attribute definitions. When default-attribute storage is full, defineAttribute doubles allocDefaultAtts and multiplies the result by sizeof(DEFAULT_ATTRIBUTE) for reallocation without first checking either operation. Attacker-controlled XML must drive enough default-attribute definitions to overflow the allocation math; upstream bounds the impact as denial of service or more.

CVSS severity9.8
Critical
EPSS probability3.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in Expat before 2.4.3 allows remote attackers to interrupt XML-parsing services via crafted XML attribute definitions. When default-attribute storage is full, defineAttribute doubles allocDefaultAtts and multiplies the result by sizeof(DEFAULT_ATTRIBUTE) for reallocation without first checking either operation. Attacker-controlled XML must drive enough default-attribute definitions to overflow the allocation math; upstream bounds the impact as denial of service or more.

The record

CVE
CVE-2022-22824
Published
Jan 8, 2022
Updated
May 5, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-190, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 8, 2022CVE publishedPublication date reported by the CVE source.
  2. May 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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